Question

An arithmetic sequence has a first term of 10 and a sixth term of 40. What is the 20th term of this sequence?

Answer 1

In An arithmetic sequence will add or subtract the same thing each time to find the next term. In this case we start with 10 and need to get to 40 on the 6th term. This is a difference of 30 that needs to be divided by 5 open spaces. You are adding 6 each time.

10, 16, 22, 28, 34, 40, _,_,_,_, 70, _,_,_,_,100,_,_,_, 124.

Another way to do this would be to look at the 5th term and multiply it by 4 to get to the 20th term. 34 x 4 = 124.

Answer 2

Answer:124

Explanation:

This is an arithmetic sequence

The nth term of an arithmetic sequence is Tn = a + (n-1)d

a is the first term.

n is the number of terms

d is the common difference

a is 10

The sixth term T6 = 10 + (6-1)d = 40

T6 = 10 - 5d = 40

5d = 40 - 10

5d = 30

d = 6

To get the 20th term T20

T20 = 10 + (20-1)6

T20 = 10 + 19(6)

T20 = 10 + 114

T20 = 124